Field of the Invention
The present invention relates to a transport system in a machine that processes printing material. The machine includes a guide device with at least one diverter, at least one runner that can be moved along the guide device, and an electric linear drive with a primary part comprising cores and a secondary part comprising the runner.
Furthermore, the present invention relates to a method for manufacturing a primary part of an electric linear drive, in which a number of cores of the primary part are provided with windings.
It has become known, in machines which process printing material, for example in printing presses, to transport the printing material to be processed, for example printing material sheets (“sheets” in the following text), by means of a transport system based on electric linear drives.
Furthermore, it has become known, in machines which process printing material, for example in web-fed printing presses, to thread a printing material web to be processed (“web” in the following text) into the machine before the actual printing process by way of a transport system based on electric linear drives.
Furthermore, it is known to branch off transport systems and/or to bring them together and to equip them with switchable diverters for this purpose. As the carriages or slides of the system that follow one another are often at only short distances from one another, it is necessary to provide diverters with short switching times and high switching dynamics.
Prior art diverters can be designed as mechanically active or mechanically passive diverters, that is to say they comprise movable mechanical components, for example, rail sections, to change the traveled path, or they do not comprise such components.
Commonly assigned German patent DE 196 21 507 C1 (cf. U.S. Pat. No. 5,809,892) discloses a web threading device for web material, having a mechanically active diverter. Here, the device has a guide rail in which a pulling device for threading the web can be moved. The forward drive is produced by an electric linear drive which has a stator comprising electromagnets configured as cores of magnetizable material with coils in each case wound around them. The cores can be connected to one another via pole laminations. Furthermore, the linear drive has, as runner, the pulling device to which two or more permanent magnets or else closed, electrically excitable coils are fastened.
The pulling device can be configured as an elongate link chain whose length is greater than the distance between two adjacent drive stations configured as coils.
Furthermore, the device has one or more switchable diverters which are each configured as a rotatable disk on which sections of the guide rail which are bent in each case in different directions are arranged. A web path for the threading of the web can be set as a function of the rotary position of the disk.
When the diverter is switched, only sections of the guide rails are moved. The drive stations remain stationary.
The diverter described can only be used in conjunction with the pulling device designed as a link chain, as no drive stations are provided in the region of the diverter and the pulling device therefore has to be gripped in drive terms by drive stations which are arranged upstream of or downstream of the diverter.
Commonly assigned European patent EP 0 907 515 B1 (cf. U.S. Pat. No. 6,240,843) discloses a transport system for sheets. There, it is proposed to provide a transport system based on electric linear drives in a sheet-fed offset printing press, which transport system transports the sheets from a first to a second printing unit by means of sheet holding means which are arranged on forward drive elements and are configured as gripper crossmembers.
Here, individual links of the forward drive elements which are configured as link chains and form the runners of the drive are composed of magnetic material, for example of permanent magnets. The drive stations which form the stator of the drive contain known electromagnetic coils which produce a moving electromagnetic field for driving the forward drive elements forward.
The transport system has a guide device with a mechanically passive diverter, which can be formed, for example, by two additional drive stations which are arranged at the beginning of a respective branching path of the transport system and are alternately supplied with current in accordance with the path to be taken (that is to say, electromagnetic fields are deliberately turned on and off in parts of the transport path to produce lateral guiding forces), as a result of which the forward drive elements are conveyed into one path or into the other path.
The proposed solution has the problem that although the provided design of the diverter as a mechanically passive diverter, that is to say without moving components, permits rapid switching of the diverter and an arrangement of the branching paths without undercuts, it can be undesirably restricted in relation to the guiding accuracy of the forward drive elements in the region of the diverter, compared with the rigid guidance in mechanically active diverters.
Furthermore, passenger transport systems based on electric linear drives are known, in which switchable diverters are provided for branching the transport paths.
A system of that type is described in each case in Japanese patent applications JP 59-6763 A and JP 5-140903 A. The switchable diverters described in those documents are designed in such a way that not only guide devices, for example rail sections, are moved, but also the stator of the drive together with said guide devices. A system of this type thus has the problem that elements having a great mass have to be moved in order to switch or actuate the diverter, with the result that rapid switching of the diverter with short switching times does not appear to be possible. However, slow switching appears acceptable in the field of passenger transport systems, as the individual trains of the system are at large distances from one another.
Furthermore, pivoting diverters or bending diverters based on an electric linear drive (for example, in the case of the Maglev train system Transrapid®) are known from the field of passenger transport systems. In those diverters both the rail sections and the stator are moved by bending. For this purpose, however, high actuating forces and long actuating paths are required, which leads to lower actuating dynamics.
Finally, it is also possible to exchange the entire section of the transport system, including rails and stator, in the region of the diverter. This does not permit high switching dynamics either, however, on account of the masses to be moved.